1. Field of the Invention
The invention relates to an auxiliary blow nozzle for an air jet weaving loom. Such auxiliary nozzles have an air flow channel with an entrance opening and a nozzle end section with an exit opening.
2. Description of the Related Art Including Information Disclosed in an Information Disclosure Statement
U.S. Pat. 4,987,930 discloses an auxiliary blow nozzle wherein the exit opening in the nozzle end section has a longitudinal central axis angled relative to a longitudinal central axis of the air flow channel. The known nozzle further includes a longitudinal section extending from said nozzle end section toward said entrance opening, said longitudinal section having an approximately elliptically formed outer circumference, an envelope curve reaching partially around said longitudinal central axis of said exit opening. The envelope curve defines the free end of said nozzle end section. The envelope curve has a radius R.sub.1, whereby the envelope curve is rounded toward neighboring surfaces.
Auxiliary blow nozzles having the above known features, are used in air nozzle weaving looms. The longitudinal axis of the exit opening for the air stream extends rectangularly to the extension of the envelope curve of the free end of the auxiliary blow nozzle or rectangularly to the longitudinal central axis of the approximately elliptical outer circumference of the nozzle body. Such a construction requires for the use of the auxiliary blow nozzle in practice that for an optimal effectiveness of the air stream on the weft thread to be inserted into the weft insertion channel of a reed, the longitudinal central axis of the exit opening is tilted at an angle of a few angular degrees in the horizontal plane relative to the warp threads of a weaving warp, or is directed at a few angular degrees toward the weft insertion channel of the reed. However, such an alignment has the disadvantage that during the immersion of the auxiliary blow nozzles into the lower shed of a weaving warp, not all concerned warp threads, which are touched or even briefly lifted by the free end of the nozzle, slide off symmetrically from this free nozzle end. Such an alignment further means that the repeated immersion of the auxiliary blow nozzles, which is a technical condition of weaving, into the lower warp, leads to damaging of the respective warp threads, when the longitudinal axis of the approximately elliptical outer circumference is not aligned in parallel to the course of the warp threads. These damages are noticeable in the produced fabric and eventually appear as weaving faults in the fabric.
Auxiliary blow nozzles are further known from European Patent Publication EP 0,145,824, which also have a structural assembly as described above. The known nozzle has a structurally fixed, longitudinal central axis of its exit opening which is angled relative to the course of the envelope curve, which forms the free end of the nozzle body, or relative to the longitudinal axis of the approximately elliptical cross-section of the nozzle body. The elliptical cross-section is congruent to the envelope curve. Such a known construction aims at achieving the following:
(a) an optimal effectiveness of the air stream on the weft thread, and PA1 (b) an optimal adaptation of the outer contour of the nozzle body end section to the course of the warp threads.
However, such a known construction still has a disadvantage in that the longitudinal central axis of the exit opening extends at an angle of more than 90.degree. to the longitudinal axis of the elliptical form of the nozzle body end section. That means that it is more difficult to produce the exit opening, compared to an exit opening aligned at a right angle to the longitudinal axis of the elliptical outer circumference.